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United States Patent |
6,185,477
|
Palm
,   et al.
|
February 6, 2001
|
System for automating the control and regulation of machines and systems in
the plastics industry
Abstract
A system for automating the control and regulation of machines and systems
in the plastics industry, in particular for blow molding machines, having
programmable logic controllers (PLC), via which control and regulation
functions of the machines and systems can be implemented as desired. The
programmable logic controllers (PLC) have at least one operating and
monitoring device and a local bus (user platform), and are further
provided with digital technology blocks (10) which simulate individual
electric circuit components and which can be used to implement the desired
control and regulation functions in a modular fashion. The digital
technology blocks (10) are connected to one another and to the user
platform via data interfaces.
Inventors:
|
Palm; Berthold (Koln, DE);
Schovenberg; Wolfgang (Koln, DE)
|
Assignee:
|
Siemens Aktiengesellschaft (Munich, DE)
|
Appl. No.:
|
044679 |
Filed:
|
March 19, 1998 |
Foreign Application Priority Data
| Sep 19, 1995[DE] | 195 34 768 |
Current U.S. Class: |
700/197; 700/18 |
Intern'l Class: |
B29C 039/00; G05B 011/01 |
Field of Search: |
700/18,17,86,197,200,201
|
References Cited
U.S. Patent Documents
5062052 | Oct., 1991 | Sparer et al.
| |
5177420 | Jan., 1993 | Wada et al. | 318/568.
|
5182716 | Jan., 1993 | Stroud et al. | 700/206.
|
5613115 | Mar., 1997 | Gihl et al. | 717/1.
|
5777869 | Jul., 1998 | Welch | 700/18.
|
Foreign Patent Documents |
0375487 | Jun., 1990 | EP.
| |
0603560 | Jun., 1994 | EP.
| |
2646536 | Nov., 1990 | FR.
| |
9311475 | Jun., 1993 | WO.
| |
Other References
T. Gerstner et al., "Rationelles Projektieren von
Automatisierungssystemen," ATP Automatisierungstechnische Praxis, vol. 36,
No. 12 (Dec. 1994), pp. 42-45.
|
Primary Examiner: Lee; Thomas C.
Assistant Examiner: Patel; Nitin
Attorney, Agent or Firm: Sughrue, Mion, Zinn, Macpeak & Seas, PLLC
Parent Case Text
This is a Continuation of International Application PCT/DE96/01667, with an
international filing date of Sep. 5, 1996, the disclosure of which is
incorporated into this application by reference.
Claims
What is claimed is:
1. A system for automating open-loop control functions and closed-loop
regulation functions of plastics-processing machines and systems,
comprising:
a user platform comprising at least one input device, at least one monitor,
and a local bus; and
at least one programmable logic controller for implementing at least one of
the control or regulation functions of the machines or systems, said
programmable logic controller comprising:
digital technology blocks, which simulate application-specific electric
circuit details and which are used to implement, in modular fashion as
function modules, the control or regulation functions that are necessary
for a specific application, said technology blocks being connected to one
another and to said user platform via data interfaces, and said technology
blocks comprising:
a plurality of organization modules, some of which are organization modules
for the function modules, some of which are organization modules for
sub-modules for the function modules, and some of which are organization
modules for organization blocks of the function modules.
2. The system as claimed in claim 1, wherein the system automates open-loop
control functions and closed-loop regulation functions of a blow molding
machine.
3. The system as claimed in claim 1, wherein the sub-modules are basic
modules for implementing necessary, rudimentary steps of the automated
control and regulation functions.
4. The system as claimed in claim 3, wherein the sub-modules are basic
modules for implementing PID closed-loop control functions or analog-value
sensing.
5. The system as claimed in claim 1, wherein at least one of the
organization blocks is for starting up the plastics-processing machine.
6. The system as claimed in claim 1, wherein one of said technology blocks
comprises an input value function module for processing input values,
adjusting an offset and scaling the input values.
7. The system as claimed in claim 6, wherein said one technology block is
provided for setting a wall thickness for a blow molding machine.
8. The system as claimed in claim 1, wherein one of said technology blocks
comprises a process control function module for implementing process
control for a memory head operation.
9. The system as claimed in claim 8, wherein said one technology block is
provided for setting a wall thickness for a blow molding machine.
10. The system as claimed in claim 1, wherein one of said technology blocks
comprises a profile calculation function module for calculating a wall
thickness profile and an ejection profile on the basis of specified
setpoint values with interpolation values.
11. The system as claimed in claim 10, wherein said one technology block is
provided for setting a wall thickness for a blow molding machine.
12. The system as claimed in claim 1, wherein one of said technology blocks
comprises a nozzle setpoint value specification function module for
specifying nozzle setpoint values.
13. The system as claimed in claim 12, wherein the nozzle setpoint value
specification function module permits a current profile value to be
logically linked to process engineering parameters for basic gap, program
selection, profile factor and dynamic round gap.
14. The system as claimed in claim 12, wherein said one technology block is
provided for setting a wall thickness for a blow molding machine.
15. The system as claimed in claim 1, wherein one of said technology blocks
comprises a function module implementing a sliding position control for at
least one of open-loop control and closed-loop regulation of an ejection
procedure.
16. The system as claimed in claim 15, wherein said one technology block is
provided for setting a wall thickness for a blow molding machine.
17. The system as claimed in claim 1, wherein one of said technology blocks
comprises a function module for implementing a hose length closed-loop
control.
18. The system as claimed in claim 17, wherein the hose length closed-loop
control is implemented by means of a photoelectric cell.
19. The system as claimed in claim 17, wherein said one technology block is
provided for setting a wall thickness for a blow molding machine.
20. The system as claimed in claim 1, wherein one of said technology blocks
comprises a function module for implementing a liquid-filling level
closed-loop control.
21. The system as claimed in claim 20, wherein the liquid-filling level
closed-loop control is performed, in synchronism with a machine clock, by
specifying setpoint values of an extruder.
22. The system as claimed in claim 20, wherein said one technology block is
provided for setting a wall thickness for a blow molding machine.
23. The system as claimed in claim 1, wherein one of said technology blocks
comprises a function module for implementing an extruder open-loop
control.
24. The system as claimed in claim 23, wherein the extruder open-loop
control controls a plurality of extruders interacting in a cascade mode,
in such a manner that specifying setpoint values for the master extruder
determines rotational speeds of the slave extruders.
25. The system as claimed in claim 23, wherein said one technology block is
provided for setting a wall thickness for a blow molding machine.
26. The system as claimed in claim 1, wherein one of said technology blocks
comprises a function module for monitoring quality of fabricated products.
27. The system as claimed in claim 26, wherein the quality monitoring
function module monitors wall thicknesses of fabricated products.
28. The system as claimed in claim 26, wherein the quality monitoring
function module monitors quality of fabricated products with reference to
master curves with an adjustable tolerance band.
29. A system for a programmable logic controller, comprising:
digital technology blocks, which simulate application-specific electric
circuit details and which are used to implement, in modular fashion as
function modules, control or regulation functions for a specific
application, said technology blocks comprising:
a plurality of organization modules, some of which are organization modules
for the function modules, some of which are organization modules for
sub-modules for the function modules, and some of which are organization
modules for organization blocks associated with a plurality of the
function modules.
Description
FIELD OF AND BACKGROUND OF THE INVENTION
The invention relates to new and useful improvements in an automation
system for the control and regulation of machines and systems used e.g. in
the plastics industry, in particular blow molding machines. More
particularly, the invention relates to such automation systems having
programmable logic controllers (PLC), which can be used to implement the
open-loop and closed-loop control functions of the machines and systems as
desired, and which have at least one operating and monitoring unit and a
local bus (user platform). The programmable logic controllers (PLC) are
provided with digital technology blocks which simulate electrical,
application-specific switching details. These technology blocks are used
to implement, in a modular fashion, the open-loop and closed-loop control
functions that are necessary for a particular application. They can be
connected to one another and to the user platform via data interfaces.
Plastics processing machines controlled by means of programmable logic
controllers are known in the art. One representative such system is
described in U.S. Pat. No. 5,062,052, the disclosure of which is
incorporated herein by reference. In the past, it has been customary to
use special hardware components, i.e. special assemblies, to automate
machines in the plastics industry, in particular those for blow molding
and injection molding. These known special assemblies have hardware and
software which are specially designed for a specific, respective task. The
results achieved with the plastics machines are good, but the control
systems are highly complex. To cope with new or modified products, both
the control programs and the special assemblies have to be adapted to the
new machine conditions. Modifications sometimes also require new hardware
components.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to provide a system for
automating the control and regulation of machines and systems in the
plastics industry, which, in contrast to conventional systems, can easily
adapt its control configuration and its scope of performance to the
requirements of the specific task at hand without modifying the hardware
or the basic software. Another aim is to enable the user to perform these
adaptations without needing an in-depth knowledge of such systems, through
the use of standardized modules, so-called basic modules.
SUMMARY OF THE INVENTION
These and other objects are achieved in that the technology blocks of the
automation system are provided with organization modules. Some of these
modules are for function modules which, in turn, have sub-modules in
organization modules, these being, in particular, basic modules which can
be used to perform the necessary basic steps for automation, for example
PID regulating functions, analog-value sensing, etc. Additionally, some of
these organization modules have organization blocks, for example for
starting up machines, etc.
Designing the automation system in this way obviates the need for
previously used, pluggable function modules, known, e.g., from EP 0 603
560 A1, the disclosure of which is hereby incorporated by reference. The
complexity of the hardware is correspondingly lower and it is possible to
use modular software throughout. This software considerably improves the
planning and implementation of the open-loop control and closed-loop
regulation of plastics-processing machines, especially linked ones. The
solution according to the invention has a software structure which is
particularly suitable for plastics-processing machines and which is not
known from the general prior art of modular software engineering. his
prior art is found, for example, in EP 0 375 487 A1 and FR 2 646 536,
which describe general forms of automatic-machinery programs.
Function modules, which in turn have sub-modules, in particular basic
modules with which the necessary basic steps of the automation can be
carried out, for example PID control functions (Proportional, Integral,
Differential, i.e., proportional plus floating plus derivative control),
analog value sensing, etc., make it possible to implement all the
necessary closed-loop and open-loop functions of plastics-processing
machines in an interactive way.
Independent technology functions can be implemented in separate technology
software blocks. Each technology block contains all the mechanisms and
functions which are necessary for the application of the technology and
the integration of the block into the control environment. For blow
molding machines, the following technology blocks, among others, can be
implemented:
temperature closed-loop control
travel sensing
wall thickness open-loop control with mandrel position closed-loop control
closed-loop-controlled blow molding movement.
The setting of the wall thickness is particularly important for the wall
thickness open-loop control and mandrel position closed-loop control of
blow molding machines. Here, use is made of various function modules
having specific basic modules which relate to specific sub-functions
during blow molding.
In particular, the functions of the various function modules include, for
example, input value treatment, scaling, etc. as well as further
functions, for example, process control, profile calculation, nozzle
setpoint value specification, open-loop control and closed-loop control of
the ejection procedure, and tube length closed-loop control, which is
carried out using a photoelectric cell. A function module is also used
when a plurality of extruders interact, for example when processing
different grades of material. The same applies to quality monitoring of
the products, and also to liquid filling level closed-loop control, which
is carried out in synchronization with the machine clock by means of the
setpoint value specification of the respective extruder.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in more detail below with the aid of
diagrammatic, exemplary embodiments in the drawing, in which:
FIG. 1 shows the software structure of an automation system according to
the invention, and
FIG. 2 shows a conventional automation system, various components of which
are also utilized by an automation system according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 2, which shows a conventional system from which the operating and
monitoring levels are taken, reference numeral 1 designates a programmable
logic controller (PLC), for example a Siemens SIMATIC S5-115U, and 4
designates an operating and monitoring unit with screen and keyboard. The
PLC 1 and the operating and monitoring unit 4, which are usually separate,
are connected to one another by means of a data line 6. Both the
technology assemblies 2 and 3, which interact with the PLC 1 and are
replaced according to the invention, and the input and output assembly 5
are arranged in the direct vicinity of the PLC, for example in the same
rack. All of these assemblies are preferably interconnected by means of a
rear-mounted bus or the like, to enable them to communicate.
FIG. 1 is a schematic view of the details of an automation system according
to the invention and peripheral components. Reference numerals 10-10"
designate various technology blocks with respective organization modules
11. The technology block 10 shown in detail is, for instance, directed to
setting a wall thickness for a blow molding machine. The organization
modules 11 are supplied with the data necessary for the production
sequence from an internal data memory 12 in the technology block 10 and
from external data memories 13. These data comprise orders, coordination
data, addresses, parameters, actual values, curves, etc. Some of the
organization modules 11, according to the invention, are connected to
basic modules 14 (standard program blocks) and some organization modules
11 are connected to function modules 15, representative individual
functions of which are described in greater detail below. Some of the
organization modules 11 themselves contain organization blocks 16, for
example for start-up of the machine, execution of cycles, etc., or
reaction of the machine in response to an alarm. The technology blocks 10
are capable of running on the CPU platform 17, which is connected to the
memory 18 for planning and design data. A preferred embodiment of a CPU
suitable for use in the CPU platform 17 is the standard CPU of a Siemens
SIMATIC S7-300 programmable logic controller.
As noted above, the function modules 15 make it possible to implement a
wide range of control and regulation functions for plastic molding
machines and the like. For instance, in the context of a technology block
10 for setting a wall thickness in a blow molding machine, function
modules include, by way of example, any of the following, alone or in
combination:
an input value function module 15 which can be used to process input
values, adjust an offset and/or scale the input values;
a function module 15 which can be used to carry out processing control for
a memory head operation;
a function module 15 according to which a wall thickness profile and
ejection profile is calculated, e.g., on the basis of specified setpoint
values with interpolation values;
a function module 15 for specifying nozzle setpoint values, and in which
the current profile value can be logically linked to process engineering
parameters such as basic gap, program selection, profile factor and
dynamic round gap parameters;
a function module 15 for open-loop and/or closed-loop control of the
ejection procedure, and for carrying our sliding position control;
a function module 15 which can be used to carry out a hose length
closed-loop control, in particular by means of a photoelectric cell;
a function module 15 which can be used to carry out a liquid-filling-level
closed-loop control, in particular in synchronization with a machine
clock, by specifying setpoint values of the extruder;
a function module 15 with which an extruder open-loop control can be
carried out, in particular for a plurality of extruders interacting in a
cascade mode, whereby specifying setpoint values of the master extruder
determines the rotational speed of the slave extruders; and
a function module 15 for monitoring the quality (e.g. wall thickness) of
the fabricated products, for example with reference to master curves with
an adjustable tolerance band.
Data are exchanged between the technology functions and the communication
files as well as, for example, with an operating and monitoring unit, a
programming unit and the user programs in the PLC-CPU 17. This exchange of
data takes place via data interfaces within the system. These data
interfaces are not components of the technology blocks 10, but instead are
advantageously made available and administered by the user platform.
Access to the process peripherals within the user platform preferably
proceeds directly from the technology blocks 10. The drivers necessary for
this are therefore located here. On the other hand, feedback for the
technology functions to the PLC-CPU 17 is advantageously provided via
interrupt.
In summary, the CPU of a SIMATIC S7-300 is advantageously used as the basis
for a comprehensive technological solution in which it is possible to run
any modular technology blocks which together provide a complete open-loop
and closed-loop control system to meet any desired technological
requirements in plastics machines.
At the same time, both the functionality and the speed of the known, costly
solutions with special assemblies are at least matched, in some cases even
exceeded.
The above description of the preferred embodiments has been given by way of
example. From the disclosure given, those skilled in the art will not only
understand the present invention and its attendant advantages, but will
also find apparent various changes and modifications to the structures
disclosed. It is sought, therefore, to cover all such changes and
modifications as fall within the spirit and scope of the invention, as
defined by the appended claims, and equivalents thereof.
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